Fatty compounds, more particularly unsaturated fatty alcohols, are important intermediate products for a large number of products of the chemical industry, for example for the production of surfactants and cosmetic products. An overview of this subject was published, for example, by U. Ploog et al. in Seifen-Ole-Fette-Wachse 109, 225 (1983).
Unsaturated fatty alcohols cannot be produced on the basis of petrochemical raw materials and processes. Instead, they are produced from more or less unsaturated fatty acids or methyl esters thereof based on renewable raw materials which are hydrogenated with the double bonds intact, for example in the presence of chromium- and/or zinc-containing mixed oxide catalysts [cf. Ullmann's Enzyklopaedie der technischen Chemie, Verlag Chemie, Weinheim, 4th Edition, Vol. 11, pages 436 et seq.].
Basically, unsaturated fatty alcohols can be produced in three ways:
1. Fats and oils are subjected to pressure hydrolysis with water. After removal of the water-containing glycerol, split fatty acids representing mixtures of saturated and unsaturated fatty acids are obtained. Since the co-hydrogenation of these acids is unable to influence the ratio of saturated and unsaturated components, it is only possible in this way to obtain fatty alcohols with a low iodine value below 80 and preferably in the range from 50 to 55. PA0 2. The separation of saturated and unsaturated fatty acids by distillation is only possible with a disproportionately high outlay on equipment. In contrast to (1), however, the split fatty acids can be converted by "roll-up separation" into a predominantly saturated fatty acid cut and a predominantly unsaturated fatty acid cut. Hydrogenation of the unsaturated fatty acid cut gives technical oleyl alcohols with iodine values of around 80 to 85 which, on an industrial scale, are further processed by fractional distillation or winterizing to form products with iodine values of 90 to 100. PA0 3. It is also possible to subject highly unsaturated vegetable oils to transesterification in which the methyl esters accumulate with a relatively small percentage of saturated homologs. Roll-up separation is neither possible nor necessary in this case because the hydrogenation directly provides highly unsaturated fatty alcohols (iodine value &gt;100). PA0 The products obtainable by method 1 have an iodine value below 80 and are wax-like. Apart from the unfavorable solidification point, they do of course have only some of the advantages associated with the unsaturated structure. PA0 Fats and oils with iodine values of 40 to 70, for example beef tallow, lard, palm oil or palm stearin, are normally used as raw materials for method 2. The resulting fatty alcohols have an iodine value of 90 to 100 and, by virtue of their property profile, are the most suitable for use on an industrial scale. However, they are often unsatisfactory both in regard to their color and in regard to their odor quality and have an unfavorably high solidification or cloud point for many applications. The same also applies to unsaturated fatty alcohols with iodine values in the same range based on conventional new sunflower oil which, on account of its high content of oleic acid, could also be used as a starting material despite its low content of polyunsaturated fatty acids. PA0 Rapeseed oil, olive oil, linseed oil or peanut oil, for example, are suitable for the production of highly unsaturated fatty alcohols by method 3. However, highly unsaturated fatty alcohols, for example those based on new rapeseed oil low in erucic acid, contain a significant percentage of polyunsaturated homologs and, accordingly, are susceptible to autoxidation processes. PA0 (a) transesterifying new LS sunflower oil with an oleic acid content of more than 85% by weight and a stearic acid content of less than 3% by weight with methanol and PA0 (b) hydrogenating the resulting methyl esters in known manner to form the corresponding unsaturated fatty alcohols with iodine values of 90 to 100. PA0 alkoxylation; PA0 alkoxylation, sulfation and neutralization; PA0 sulfation and neutralization; or PA0 esterification with aliphatic carboxylic acids containing 1 to 22 carbon atoms and 0 and/or 1 to 3 double bonds. PA0 (a) new LS sunflower oil with an oleic acid content of more than 85% by weight and a stearic acid content of less than 3% by weight is transesterified with methanol and PA0 (b) the resulting methyl esters are hydrogenated in known manner to form the corresponding unsaturated fatty alcohols with iodine values of 90 to 100. PA0 Alkoxylation. Alkoxylates of the unsaturated fatty alcohols are obtained in known manner by addition of ethylene and/or propylene oxide in the presence of basic catalysts, for example sodium methylate or calcined hydrotalcite, and may have both a conventional homolog distribution and a narrow homolog distribution. The alkoxylates are suitable, for example, as raw materials for detergents, as emulsifiers in the textiles field, in drilling and cutting oils and in cosmetic formulations. PA0 Alkoxylation/sulfation. Ether sulfates of the unsaturated fatty alcohols are obtained in known manner by alkoxylation, subsequent sulfation with gaseous sulfur trioxide or chlorosulfonic acid and, finally, neutralization with bases. The products are suitable as raw materials for detergents. PA0 Sulfation. Fatty alcohol sulfates based on the unsaturated alcohols are obtained in known manner by sulfation with gaseous sulfur trioxide or chlorosulfonic acid and subsequent neutralization with bases. The products are also suitable as detergents for raw materials and as textile auxiliaries. PA0 Esterification. Esters of the unsaturated fatty alcohols are obtained in known manner by catalytic reaction with aliphatic carboxylic acids containing 1 to 22, preferably 6 to 22 and more preferably 12 to 18 carbon atoms and 0 and/or 1 to 3 double bonds. Typical examples are reactions of a technical oleyl alcohol according to the invention (iodine value 95) with acetic acid, C.sub.6-10 head-fractionated fatty acid, lauric acid, palmitic acid, stearic acid, oleic acid, C.sub.12/14 cocofatty acid, C.sub.12/18 cocofatty acid or C.sub.16/18 tallow fatty acid. The products are suitable, for example, as oils for the production of cosmetic formulations.
The three processes mentioned have long been commercially used for the production of unsaturated fatty alcohols which, unfortunately, are attended by a number of disadvantages:
Accordingly, the problem addressed by the present invention was to provide unsaturated fatty alcohols with an iodine value of 90 to 100 based on vegetable raw materials--and corresponding derivatives--which would be distinguished in particular by improved low-temperature behavior.